The subject invention relates to amide modified saturated polyester polyols. More particularly, it relates to amide modified saturated polyester polyols of specified acid number, hydroxyl number and amine number and their process of production. The polyester polyols are especially useful in making two-package urethane coatings.
Saturated polyester polyols are a well-known class of materials. One field of use they have found has been in their reaction with isocyanates to produce urethane coatings. The urethane coatings are known for their excellent durability, chemical resistance, abrasion resistance, adhesion, toughness and flexibility. Coatings for wire, storage tanks, automobiles, etc., are among the many end-uses found for the urethane coatings because of the outstanding properties they impart to these products.
One-package urethane coatings (based on blocked isocyanates which react with --OH groups at elevated temperatures) and two-package urethane coatings (based on the mixing of an isocyanate and a polyol at the time of coating to form high polymers) are both extensively used. Each type of urethane coating offers advantages in terms of application convenience, coating properties, etc. Generally, the two-package urethane coatings are noted for their chemical resistance and flexibility. Of course, a wide range of coating properties are available depending on the nature of the individual components and amounts thereof used in the urethane producing reaction.
The saturated polyester polyols in particular have been modified in various ways to achieve different desired properties. For example, polyesters have been treated with imines so as to obtain modified polyesters. Such modified polyesters have been further reacted with isocyanates to produce a urethane coating satisfactory in many respects. U.S. Pat. No. 3,494,847 is an example of the use of imines to modify polyesters. However, doubts as to the industrial safety of certain imines has made their use somewhat restricted.
It has now been found that amide modified saturated polyester polyols can be made by a process which avoids the use of imines and which gives an amide modified polyester polyol possessing superior characteristics, especially with regard to dispersing pigments and stabilizing the dispersions obtained.
It is accordingly an object of this invention to produce amide modified saturated polyester polyols.
It is another object of this invention to produce amide modified saturated polyester polyols by a convenient and safe method.
These and other objects will become apparent from the description which follows.
As used herein all percentages and ratios are by weight unless otherwise indicated.